Initial impression doing quick A-B flips, with volume of the uDAC at about 3:00 for what seemed like a level level-match. Dell Laptop & I-Tunes as the transport vs Marantz DVD player from maybe 5 years ago.
The DVD player sounds drier and harsher in comparison. The uDAC combo is more liquid, more analog-like. More ease to the sound. Too many people around to try to evaluate something like imaging or bass. Easier-on-the-ear sound decides the contest right off the bat, though!
Amp is a NAD C340 integrated and speakers a pair of NHT SB2s (6.5 two-way), FWIW.
Just did a quickie headphone test with my son's Grado SR80s- not a very hard test for the uDAC. I had a so-so set of Senns sitting around and it seemed to do more for them. But the amp should definitely help big time on the Grados when compared to the bad sound (he tells me) of the computer's headphone out. Sounded similar to the NAD's headphone out, I thought. His Marantz receiver phone out may have a nicer sound, IIRC. Worst case is that one problem (the computer headphone out) is solved. I'll ask him in a few months about the headphone part.